Your local contact:test method
insulation resistance (electrical)
For this purpose, a distinction is made between active parts and protective earth conductor or touchable conductive parts TEST VOLTAGE and the resulting insulation resistance measured.
A sufficient insulation resistance ensures that no dangerous leakage currents can occur during intended operation.
Insufficient insulation resistance can – especially in conjunction with an additional protective earth conductor fault – lead to impermissibly high touch voltages on touchable conductive parts. In such a case, touching these metallic parts can cause a dangerous touch current to flow through the human body to earth.
For Class II devices, an insulation fault on touchable metallic parts poses a particular risk, as these devices do not have a protective earth conductor, and thus no defined diversion of the fault current can occur.
The measurement of insulation resistance is performed by applying a DC test voltage, typically 500 V DC, between the current-carrying conductors and earth or touchable conductive parts. Often, the current-carrying conductors are connected, so that the total resistance of the parallel-connected insulation paths is determined. However, measurement in individual test steps between the individual conductors is also fundamentally possible.
Since the test is performed with DC voltage, insulation Capacitances do not influence the measurement result. Only the ohmic component of the insulation resistance is measured.
For larger insulation Capacitances, an extended test time may be required to ensure the complete charging of the insulation Capacitances at the beginning of the test. Depending on the device under test, this can take several tenths of a second.
Insulation resistance tests are performed manually by scanning multiple test points with safety test probes. However, fully automatic test devices with extensive matrix or switching systems are mostly used. This enables automated testing at multiple test points sequentially. The number of matrix points is virtually unlimited due to the system design.
The image shows a simple switch-over solution that allows various test points to be tested against a central reference point, such as the protective earth conductor (PE).
The image shows a two-wire matrix for automatic testing of all test point combinations according to the "every against every" principle.
Discharge after the insulation resistance test
During the insulation resistance test, the Capacitance present in the device under test is charged. After the test voltage is switched off, this charge initially remains, meaning a dangerous Residual voltage can still be present on the device under test. This poses an acute risk of electric shock to personnel and a hazard for subsequent work steps.
For this reason, it is imperative to safely discharge the device under test after the completion of the test. Modern insulation resistance test devices are equipped with built-in discharge facilities that automatically and safely discharge the device under test to a non-hazardous voltage level. Only after complete discharge may the device under test be touched or further processed.
Reliable and monitored discharge is therefore an essential part of the test and indispensable for the safety of operating personnel and the test environment.
The insulation resistance test is conducted under complex theoretical consideration using an equivalent circuit diagram consisting of 4 basic components.
These are:
- C = capacitor between the two poles
- Rs = Surface resistance
- Rpi+Cpi = Equivalent circuit diagram of the polarization index
- Riso = Insulation resistance
Why?
The device under test has an insulation resistance between the two test points. This is the resistance Riso. This resistance is typically very high, ranging from a few 100 MΩ up to 10 TΩ.
Furthermore, the device under test has a Capacitance between the two test points. This forms either between the windings to be tested or from the winding to the frame. Between the windings, it is typically smaller than from the winding to the frame. Capacitances arise between insulated metal surfaces. The larger the surfaces or the smaller the distance between the metal surfaces, the greater the Capacitance. In the stator, the windings form one metal surface and the laminated core forms the other. The larger the stator (its physical size), the larger the surfaces become, and thus the Capacitance.
Häufig hat ein Elektroprodukt blanke unisolierte elektrische Leiter. Dies gilt z.B. für einen Gleichstrommotor. Auf der Oberfläche der Leiter können sich elektrisch leitende Stäube ablagern und/oder Luftfeuchtigkeit niederschlagen. Dadurch ergibt sich eine Art Oberflächenwiderstand. Im Idealfall sollte er unendlich sein, aber manchmal kann er extrem niedrig werden (< 1 MΩ).
Electrical insulating materials, such as resins, have dipole-like molecules. These thus exhibit a +/- polarization. When a DC high voltage is applied, these molecules align with the electric field. This polarization requires a certain amount of time. This is to be simulated using an RC element.
What currents result from this?
The total insulation resistance is calculated using Ohm's Law. After applying the TEST VOLTAGE, a total current (Iges) results, which consists of 4 individual currents.
Total current = Iges = Ic + Is + Ipi + Iiso
This is: Rgiso = Uhv/Iges
Since the two currents Ic and Ipi only become zero after some time, this period must first be awaited for the accurate determination of the insulation resistance.
The charging of the capacitor occurs quickly and is usually completed within a few seconds. The goal is to charge the capacitor within a maximum of 30 seconds. After this time, Ic is therefore 0.
The charging of the polarization capacitance takes considerably longer. In the worst case, this can take up to 10 minutes for an electric motor. Therefore, under such conditions, the true insulation resistance can only be determined after 10 minutes.
What test devices does SCHLEICH supply?
- Individual test devices
- Combination test devices (combination with further safety or function tests)
- Various versions up to the range of 10 TΩ
- Manual Testing using Test Probes
- Fully automated test sequences
- Matrix with up to 500 terminals and fully automatic switch-over
- Test devices of various device classes
Standards committees
For legal reasons, we cannot in many cases make a binding statement about the Test conditions. The currently valid standards for your product to be tested are decisive for the application.
The standard may vary depending on the product's geographical area of use. Further information can also be found, among others, at the institutes listed below.
Test devices and Test systems
HandHeld
Protective earth conductor and insulation resistance test device
- protective earth resistance test up to 10 A AC
- Insulation resistance test up to 1,000 V
- Mobile use – lightweight – for indoor and outdoor applications
- Carrying strap
- Transport case
- PC software included
- Attractive acquisition costs
-
Technical Service for Hospitals
-
Rotor blade lightning protection test for wind turbines ...
GLP1-g insulation resistance test devices
- DC 50 – 1000 V | 5 mA
Ideal for
- Manual Tests with Test Tips
- Testing in a test cover, test cabinet
- Fully automatic test stations
- OEMs, system integrators
- Communication with PC, PLC, LabVIEW®
GLP2-BASIC
Protective earth conductor, insulation, high voltage, leakage current, resistance, and functional test device
- Insulation test devices
- High voltage test devices AC/DC
- “All in one” test devices
- Safety & functional test devices
- Approx. 40 device variants – combined from up to 21 test methods
- PL e, SIL 3, two-hand control Type III C, Cat. 4 safety circuit (depending on device variant and degree of hazard)
- Network
- Protocol & label printing
- Scanner …
- Technology Package for even greater ergonomics
- Desktop device or 19″ rack mounting
GLP2-MODULAR
Multifunction test device with up to 25 test methods
- “All in one”
- Safety test devices
- Safety & functional test devices
- Modularly combinable from over 25 test methods
- Up to 250 test connections
- Switching matrixes for all types of test methods
- PL e, SIL 3, two-hand control Type III C, Cat. 4 safety circuit (depending on device variant and degree of hazard)
- Network
- Protocol & label printing
- Scanner …
- Technology Package for even greater ergonomics
GLP3
Class-leading test technology unlimited
The top class of test and measurement technology for safety & function test.
- “All in one”
- Safety & functional test devices
- For complex projects
- For complex automation
- For highest demands
- Modularly combinable from over 30 test methods
- Up to 350 test connections
- Switching matrices for all types of test methods
- PL e, SIL 3, Cat. 4 safety circuit, two-hand operation 2-channel safety
- Windows 11®
- Network
- Protocol & label printing
- Industry 4.0
- Interfaces for automation such as PROFINET, EtherCAT, TCP/IP, …
- Interfaces to MES, ERP, CAQ systems, …
GLP3-M
Electric motor Test - EOL, Series and Laboratory
For production, EOL and automation
For test laboratories
Test benches for functional and safety testing of all types of Motors.
- Asynchronous Motors
- Synchronous Motors
- Linear Motors
- Stepper Motors
- BLDC
- DC Motors
- …
- Motor attachments
– Brake
– Temperature sensors
– Humidity sensors
– Auxiliary heating
– Fan
– Centrifugal switch
– Rotor position sensors, Encoders, Resolvers, Multiturn encoders …
– Electronic nameplate
MotorAnalyzer1
The entry-level model for your Motor service
CHECK YOUR MOTOR'S HEALTH!
For electric motor service and repair
For electric motor repair
For maintenance, servicing, and service
- Universal stator-, armature-, Motor- and transformer testing equipment
- 10 built-in test methods
- Automatic measurement between the three Connections of a three-phase Motor
- Built-in results database
- Transmission of the results via RS-232 or USB interface to the PC
- Mains-independent battery operation with battery status indicator
- Extremely compact design
- Ideal tool for on-site use and for the workshop
MotorAnalyzer3
The mobile ALL-IN-ONE professional model for your Motor service
CHECK YOUR MOTOR'S HEALTH!
For electric motor service and repair
For electric motor repair
For maintenance, servicing, and service
- Globally unique – the mobile ALL-IN-ONE test device
- AutoTest – the fastest troubleshooting
- Battery operation – Test nonstop
- surge test up to 3 kV | 0.45 Joule
- High voltage DC up to 6 kV
- Insulation up to 500 GΩ
- Polarization index and DAR
- LCR measurement
- Automatic measurement between the four relevant Connection points of the three-phase Motor
- three winding Connections
- one housing Connection (laminated core or Motor housing)
- Communication with
«» PC via Bluetooth
MTC2 R7
Universal winding Test devices 6, 12, 15, 30, 40 and 50 kV
MTC2 winding Test systems are very compact, fully automatic high-end Test devices for a wide variety of winding goods in development, production, and Test laboratory.
For production, EOL, automation
For test laboratory, R&D, approval, certification tests
For repair, maintenance, and service
surge test
-
- Ultra-fast 50 measurements per second
- Phase comparison between phases
- Patented peak-to-peak measurement
Partial discharge compliant with DIN EN 60034-18:2014
-
- Passive or active antenna
- Conducted coupling
ohmic resistance
-
- Winding
- Temperature sensor
insulation resistance
-
- IR
- PI
- DAR
High voltage AC optional
Test connections
-
- Standard: 4
- Optional: 7 and more
MTC3 R2
The high-end test systems for Motor production – without limit
MTC3 winding test systems are fully automatic high-end test devices for various winding goods in development, production, and test laboratories.
For production, EOL, automation
For test laboratory, R&D, approval, certification tests
- Testing of stators, rotors, transformers and inductors
- Surge test up to 15 kV
- Fully built-in partial discharge test according to IEC 61934 and DIN EN 60034-18-41
- Resistance measurement in four-wire technology with temperature compensation
- Insulation resistance test with automatic PI measurement
- Inductance test | LCR inductance measurement bridge
- High voltage test AC according to VDE standard
- Partial discharge at high voltage AC
- Insulation test DC
- Precise four-wire resistance measurement with temperature compensation down to the µΩ-space
- Rotating field test with static probe
- Expansion to up to 150 connections
- Temperature sensor test for 1, 2, 3 … x sensors
"*" indicates required fields